Remember, you can only transfer 1x without being required to sit out, but I believe grad transfers are an exception. So, you have to be careful if you decide to enter the portal. What would have happened to Dillon Gabriel if he had started classes at UCLA on Monday and on Thursday he finds out Caleb Williams is also transferring to UCLA?
Also, I think some people have a misconception of the portal. The portal does not just include football players that are academically eligible, with no discipline problems, and good enough to be an FBS starter, but there are many kids that their coach decided they couldn't play at the FBS level and the coach is pushing them out, have discipline problems, or kids with academic issues. That is why ~50% of FBS kids that enter the portal don't find a new home. I think this is why you are seeing teams recruit the top Ivy kids in the transfer portal who are grad transfers as the Ivies don't allow redshirting, the kids are experienced, and they have good academics.